Phase-field simulation of diffusion couples in the Ni–Al system

Abstract By linking thermodynamic and atomic mobility databases with two-dimensional phase-field simulation, the evolution of interdiffusion microstructures in a series of Ni–Al diffusion couples associated with the γ, γ′, and β-phases was studied. The formation and subsequent growth of the γ′-phase layer in β/γ and γ′ + β/γ diffusion couples reproduced the experimental observations well. Moreover, the effect of coherent strain on the γ – γ′ microstructural evolution, as well as that of an external compressive force on the γ + γ′/γ + γ′ diffusion couple, was investigated. The phase-field simulated concentration profiles of some of the Ni–Al diffusion couples were also compared with the corresponding experimental data and the results of one-dimensional DICTRA (DIffusion Controlled TRAnsformations) simulations. A discussion of the rafting direction was also made by comprehensively comparing the phase-field simulations with the predicted results from an elastic model.